How common is type "O" blood?

Answer by  GeorgeH (179)

On a worldwide basis, about 41% of people have type O blood, making it the most common of the four main blood types.

Answer by  Roland27 (16334)

It depends what type of O we are talking about here. The blood type O+ is actually the MOST common blood type out there. O- negative on the other hand is VERY rare. Anyone with either of the O blood types are able to give blood to anyone, but cannot receive blood from anyone who isn't an O.